272 FACULTIES OF BIRDS. 



the year another transient visit was paid, and then 

 the different sexes were plainly distinguishable. 



A remarkable example of this kind of migration is 

 afforded by the passenger-pigeon of America, the 

 history of which is given by Audnbon, in his Orni- 

 thological Biography. " The most important facts,'* 

 he says, " connected with its habits, relate to its mi- 

 grations. These are entirely owing to the necessity 

 of procuring food, and are not performed with the 

 view of escaping the severity of a northern latitude, 

 or of seeking a southern one for the purpose of 

 breeding. They consequently do not take place at 

 any fixed period or season of the year ; indeed it 

 sometimes happens, that a continuance of a sufficient 

 supply of food in one district will keep these birds 

 absent from another for years. I know, at least, to 

 a certainty, that in Kentucky they remained for seve- 

 ral years constantly, and were nowhere else to be 

 found. They all suddenly disappeared one season 

 when the maize was exhausted, and did not return 

 for a long period. Similar facts have been observed 

 in other states. 



44 In the autumn of 1813, I left my house at Hen- 

 derson, on the banks of the Ohio, on my way to 

 Louisville. In passing over the Barrens, a few miles 

 beyond Hardensburgh, I observed the pigeons flying 

 from north-east to south-west, in greater numbers 

 than I thought I had ever seen them before; and 

 feeling an inclination to count the flocks that might 

 pass within the reach of my eye in one hour, I dis- 

 mounted, seated myself on an eminence, and began 

 to mark with my pencil, making a dot for every flock 

 that passed. In a short time, finding the task which 

 I had undertaken impracticable, as the birds poured 

 on in countless multitudes, I rose, and counting the 

 dots then put down, found that one hundred and 

 sixty-three had been made in twenty-one minutes. I 



